The present invention describes N-substituted dithiocarbamate esters and their use in the treatment of biological disorders. The N-substituted dithiocarbamate esters are particularly useful in the treatment of hyperproliferative conditions such as cancer. They can also be used in the treatment of VCAM-1 mediated conditions such as cardiovascular disorders and inflammatory diseases.
A wide range of disorders involve the hyperproliferation of cells, ranging from psoriasis to benign and malignant tumors. These disorders are generally caused by a loss of control over normal cell growth, differentiation, or the process of programmed cell death (apoptosis). Many of the abnormalities that underlie these disorders, particularly cancer, occur at the genetic level. Antineoplastic agents (also known as cytotoxic agents) are often used in the treatment of hyperproliferative conditions. Therapy with antineoplastic agents is successful in the treatment of a number of malignant conditions; however, in most it is used to palliate the symptoms and to prolong life in patients with advanced disease.
Cancer is a class of tumors that is characterized by invasiveness and metastasis. It is possible to recur after attempted removal, and causes death unless adequately treated. Stedman""s Medical Dictionary, 25th Edition Illustrated, Williams and Wilkins, 1990. Approximately 1.2 million Americans are diagnosed with cancer each year, 8,000 of which are children. In addition, 500,000 Americans die from cancer each year in the United States alone. Specifically, lung and prostate cancer are the top cancer killers for men while lung and breast cancer are the top cancer killers for women. It is estimated that cancer-related costs account for about 10 percent of the total amount spent on disease treatment in the United States. CNN Cancer Facts, http://www.cnn.com/HEALTH/9511/conquer_cancer/facts/index.html, page 2 of 2, Jul. 18, 1999.
Although a variety of approaches to cancer therapy (e.g., surgical resection, radiation therapy, and chemotherapy) are available and have been used for many years, cancer remains one of the leading causes of death in the world. This is due in part to the fact that the therapies themselves cause significant toxic side-effects and re-emergence is common.
Antineoplastic agents have been described extensively in a number of texts, including Martindale, The Extra Pharmacopoeia, 31st Edition, Royal Pharmaceutical Society (1996).
Antineoplastic agents include:
(i) antifolates;
(ii) antimetabolites (including purine antimetabolites, cytarabine, fudarabine, floxuridine, 6-mercaptopurine, methotrexate, 5-fluoropyrimidine, including 5-fluorouracil, cytidine analogues such as xcex2-L-1,3-dioxolanyl cytidine and 6-thioguanine);
(iii) hydroxyurea;
(iv) mitotic inhibitors (including CPT-11, Etoposide(VP-21)), taxol, and vincristine,
(v) alkylating agents (including but not limited to busulfan, chlorambucil, cyclophosphamide, ifofamide, mechlorethamine, melphalan, and thiotepa);
(vi) nonclassical alkylating agents, platinum containing compounds, bleomycin, anti-tumor antibiotics, anthracycline, anthracenedione, topoisomerase 11 inhibitors, hormonal agents (including but not limited to corticosteroids (dexamethasone, prednisone, and methylprednisone); and
(v) androgens such as fluoxymesterone and methyltestosterone, estrogens such as diethylstilbesterol, antiestrogens such as tamoxifen, LHRH analogues such as leuprolide, antiandrogens such as flutamide, aminoglutethimide, megestrol acetate, and medroxyprogesterone), asparaginase, carmustine, lomustine, hexamethyl-melamine, dacarbazine, mitotane, streptozocin, cisplatin, carboplatin, levamasole, and leucovorin.
A more comprehensive list of antineoplastic agents includes Aceglatone; Aclarubicin; Altretamine; Aminoglutethimide; 5-Aminogleavulinic Acid; Amsacrine; Anastrozole; Ancitabine Hydrochloride; 17-1A Antibody; Antilymphocyte Immunoglobulins; Antineoplaston A10; Asparaginase; Pegaspargase; Azacitidine; Azathioprine; Batimastat; Benzoporphyrin Derivative; Bicalutamide; Bisantrene Hydrochloride; Bleomycin Sulphate; Brequinar Sodium; Broxuridine; Busulphan; Campath-IH; Caracemide; Carbetimer; Carboplatin; Carboquone; Carmofur; Carmustine; Chlorambucil; Chlorozotocin; Chromomycin; Cisplatin; Cladribine; Corynebacterium parvum; Cyclophosphamide; Cyclosporin; Cytarabine; Dacarbazine; Dactinomycin; Daunorubicin Hydrochloride; Decitabine; Diaziquone; Dichlorodiethylsulphide; Didemnin B.; Docetaxel; Doxifluridine; Doxorubicin Hychloride; Droloxifene; Echinomycin; Edatrexate; Elliptinium; Elmustine; Enloplatin; Enocitabine; Epirubicin Hydrochloride; Estramustine Sodium Phosphate; Etanidazole; Ethoglucid; Etoposide; Fadrozole Hydrochloride; Fazarabine; Fenretinide; Floxuridine; Fludarabine Phosphate; Fluorouracil; Flutamide; Formestane; Fotemustine; Gallium Nitrate; Gencitabine; Gusperimus; Homoharringtonine; Hydroxyurea; Idarubicin Hydrochloride; Ifosfamide; Ilmofosine; Improsulfan Tosylate; Inolimomab; Interleukin-2; Irinotecan; JM-216; Letrozole; Lithium Gamolenate; Lobaplatin; Lomustine; Lonidamine; Mafosfamide; Melphalan; Menogaril; Mercaptopurine; Methotrexate; Methotrexate Sodium; Miboplatin; Miltefosine; Misonidazole; Mitobronitol; Mitoguazone Dihydrochloride; Mitolactol; Mitomycin; Mitotane; Mitozanetrone Hydrochloride; Mizoribine; Mopidamol; Multialchilpeptide; Muromonab-CD3; Mustine Hydrochloride; Mycophenolic Acid; Mycophenolate Mofetil; Nedaplatin; Nilutamide; Nimustine Hydrochloride; Oxaliplatin; Paclitaxel; PCNU; Penostatin; Peplomycin Sulphate; Pipobroman; Pirarubicin; Piritrexim Isethionate; Piroxantrone Hydrochloride; Plicamycin; porfimer Sodium; Prednimustine; Procarbazine Hydrochloride; Raltitrexed; Ranimustine; Razoxane; Rogletimide; Roquinimex; Sebriplatin; Semustine; Sirolimus; Sizofiran; Sobuzoxane; Sodium Bromebrate; Sparfosic Acid; Sparfosate Sodium; Sreptozocin; Sulofenur; Tacrolimus; Tamoxifen; Tegafur; Teloxantrone Hydrochloride; Temozolomide; Teniposide; Testolactone; Tetrasodium Meso-tetraphenylporphinesulphonate; Thioguanine; Thioinosine; Thiotepa; Topotecan; Toremifene; Treosulfan; Trimetrexate; Trofosfamide; Tumor Necrosis Factor; Ubenimex; Uramustine; Vinblastine Sulphate; Vincristine Sulphate; Vindesine Sulphate; Vinorelbine Tartrate; Vorozole; Zinostatin; Zolimomab Aritox; and Zorubicin Hydrochloride.
For about four decades, the antimetabolite 5-fluorouracil (5-FU), and nucleosides which include this base (e.g., 5-fluoro-2xe2x80x2-deoxyuridine or FdUrd), have remained among the few xe2x80x9cstandardxe2x80x9d drugs effective against solid tumors in man. 5-Fluorouracil is used mainly for the treatment of colorectal, ovarian, renal, breast and head and neck cancers. 5-Fluoro-2xe2x80x2-deoxyuridine is used for the treatment of solid tumors, including hepatic metastases of advanced gastrointestinal adenocarcinomas, renal cell carcinomas, advanced ovarian cancer, and squamous cell carcinomas of the head and neck. The clinical utility of the fluoropyrimidines is limited by the host-toxicity induced by the administration of these compounds. Manifestations of the host-toxicity of the fluoropyrimidines include mainly gastrointestinal epithelial ulceration, myelosuppression and, to a lesser extent, cardiotoxicities, hepatotoxicities and neurotoxicities. A population of cancer patients is intolerant to treatment with 5-fluorouracil and 5-fluoro-2xe2x80x2-deoxyuridine. Moreover, it has also been shown that cancers, treated with fluoropyrimidines, become resistant, i.e., develop tolerance towards these drugs.
Colorectal cancer (CRC) is a multi-step process resulting from the accumulation of mutations in clonal populations of colonocytes. Mutations of the p53 tumor suppressor gene are a relatively late, yet common event in the pathogenesis of colorectal cancer, occurring in over 80% of late adenomas and carcinomas (Fearon, et al., FASEB J. 6, 2789 (1992); Srivastarva, et al., Contemp. Oncol. April 63 (192); Kline, et al., Cancer (Phila. 73, 28 (1994). Conventional therapy for advanced disease, such as cytotoxic chemotherapy and gamma-irradiation, induce DNA damage in proliferating cells. This damage, through undefined mechanism(s), signals the induction of p53, which, in turn, leads to inhibition of cellular proliferation by induction of G1 cell cycle arrest and, in some instances, apoptosis. Thus, tumors lacking functional p53 are frequently refractory to such therapies (S. C. Righetti et al., Cancer Res. 56, 689 (1996); J. S. Kovack et al., Proc. Natl. Acad, Sci. U.S.A. 93, 1093 (1996)), emphasizing the importance of developing treatments for advanced colorectal cancer that do not rely on functional p53.
The most effective single chemotherapeutic agent for advanced colorectal cancer to date remains 5-FU. The active metabolite of 5-FU, 5-fluorodeoxyuridine-5xe2x80x2-monophosphate (FdUMP), forms a complex with thymidylate synthase (TS) in the presence of reduced folate, thereby inhibiting enzyme activity, and depleting precursors for DNA synthesis. 5-FU is also incorporated into RNA, altering its processing and function, although how this correlates with cytotoxicity is unknown. Previous data suggest that 5-FU can utilize both p53-dependent and independent pathways (Pritchard, et al., Pharmacol. Ther. 72, 149 (1996)), although a loss of p53 function dramatically reduces 5-FU efficacy (B. Cohen et al., Cancer (Phila.) 67, 1859 (1991); Advanced Cancer Meta-Analysis Project, J. Clin. Oncol. 10, 896 (1992)).
VCAM-1
Adhesion of leukocytes to the endothelium represents a fundamental, early event in a wide variety of inflammatory conditions, including atherosclerosis, autoimmune disorders and bacterial and viral infections. Leukocyte recruitment to the endothelium is started when inducible adhesion molecule receptors on the surface of endothelial cells interact with counterreceptors on immune cells. Vascular endothelial cells determine which type of leukocytes (monocytes, lymphocytes, or neutrophils) are recruited, by selectively expressing specific adhesion molecules, such as vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and E-selectin. In the earliest stage of the atherosclerotic lesion, there is a localized endothelial expression of VCAM-1 and selective recruitment of mononuclear leukocytes that express the integrin counterreceptor VLA-4. Because of the selective expression of VLA-4 on monocytes and lymphocytes, but not neutrophils, VCAM-1 is important in mediating the selective adhesion of mononuclear leukocytes. Subsequent conversion of leukocytes to foamy macrophages results in the synthesis of a wide variety of inflammatory cytokines, growth factors, and chemoattractants that help propagate the leukocyte and platelet recruitment, smooth muscle cell proliferation, endothelial cell activation, and extracellular matrix synthesis characteristic of maturing atherosclerotic plaque.
VCAM-1 is a mediator of chronic inflammatory disorders such as asthma, rheumatoid arthritis and autoimmune diabetes. For example, it is known that the expression of VCAM-1 and ICAM-1 are increased in asthmatics. Pilewski, J. M., et al. Am. J Respir. Cell Mol. Biol. 12, 1-3 (1995); Ohkawara, Y., et al., Am. J. Respir. Cell Mol. Biol. 12, 4-12 (1995). Additionally, blocking the integrin receptors for VCAM-1 and ICAM-1 (VLA-4 and LFA-1, respectively) suppressed both early and late phase responses in an ovalbumin-sensitized rat model of allergic airway responses. Rabb, H. A., et al., Am. J. Respir. Care Med. 149, 1186-1191 (1994). There is also increased expression of endothelial adhesion molecules, including VCAM-1, in the microvasculature of rheumatoid synovium. Koch, A. E. et al., Lab. Invest. 64, 313-322 (1991); Morales-Ducret, J. et al., Immunol. 149, 1421-1431 (1992). Neutralizing antibodies directed against VCAM-1 or its counter receptor, VLA-4, can delay the onset of diabetes in a mouse model (NOD mice) which spontaneously develop the disease. Yang, X. D. et al., Proc. Natl. Acad. Sci. U.S.A. 90, 10494-10498 (1993); Burkly, L. C. et al., Diabetes 43, 523-534 (1994); Baron, J. L. et al., J. Clin. Invest. 93, 1700-1708 (1994). Monoclonal antibodies to VCAM-1 can also have a beneficial effect in animal models of allograft rejection, suggesting that inhibitors of VCAM-1 expression may have utility in preventing transplant rejection. Oroez, C. G. et al., Immunol. Lett. 32, 7-12 (1992).
VCAM-1 is expressed by cells both as a membrane bound form and as a soluble form. The soluble form of VCAM-1 has been shown to induce chemotaxis of vascular endothelial cells in vitro and stimulate an angiogenic response in rat cornea. Koch, A. F. et al., Nature 376, 517-519 (1995). Inhibitors of the expression of soluble VCAM-1 have potential therapeutic value in treating diseases with a strong angiogenic component, including tumor growth and metastasis. Folkman, J., and Shing, Y., Biol. Chem. 10931-10934 (1992).
U.S. Pat. Nos. 5,750,351; 5,807,884; 5,811,449; 5,846,959; 5,773,231, and 5,773,209 to Medford, et al., as well as the corresponding WO95/30415 to Emory University indicate that polyunsaturated fatty acids (xe2x80x9cPUFAsxe2x80x9d) and their hydroperoxides (xe2x80x9cox-PUFAsxe2x80x9d), which are important components of oxidatively modified low density lipoprotein (LDL), induce the expression of VCAM-1, but not intercellular adhesion molecule-1 (ICAM-1) or E-selectin in human aortic endothelial cells, through a mechanism that is not mediated by cytokines or other noncytokine signals. This is a fundamental discovery of an important and previously unknown biological pathway in VCAM-1 mediated immune responses.
The induction of VCAM-1 by PUFAs and their fatty acid hydroperoxides is suppressed by dithiocarbamate salts, including pyrrolidine dithiocarbamate (PDTC). This indicates that the induction is mediated by an oxidized signal molecule, and that the induction is prevented when the oxidation of the molecule is blocked (i.e., the oxidation does not occur), reversed (i.e., the signal molecule is reduced), or when the redox modified signal is otherwise prevented from interacting with its regulatory target.
Dithiocarbamates
Dithiocarbamates and related compounds have been reviewed extensively by several authors, including G. D. Thorn et al. in a book entitled xe2x80x9cThe Dithiocarbamates and Related Compounds,xe2x80x9d Elsevier, New York, 1962. Dithiocarbamates are transition metal chelators clinically used for heavy metal intoxication. Baselt, R. C., F. W. J. Sunderman, et al. (1977), xe2x80x9cComparisons of antidotal efficacy of sodium diethyldithiocarbamate, D-penicillamine and triethylenetetramine upon acute toxicity of nickel carbonyl in rats.xe2x80x9d Res Commun Chem Pathol Pharmacol 18(4): 677-88; Menne, T. and K. Kaaber (1978), xe2x80x9cTreatment of pompholyx due to nickel allergy with chelating agents.xe2x80x9d Contact Dermatitis 4(5): 289-90; Sunderman, F. W. (1978), xe2x80x9cClinical response to therapeutic agents in poisoning from mercury vaporxe2x80x9d Ann Clin Lab Sci 8(4): 259-69; Sunderman, F. W. (1979), xe2x80x9cEfficacy of sodium diethyldithiocarbamate (dithiocarb) in acute nickel carbonyl poisoning.xe2x80x9d Ann Clin Lab Sci 9(1): 1-10; Gale, G. R., A. B. Smith, et al. (1981), xe2x80x9cDiethyldithiocarbamate in treatment of acute cadmium poisoning.xe2x80x9d Ann Clin Lab Sci 11(6): 476-83; Jones, M. M. and M. G. Cherian (1990), xe2x80x9cThe search for chelate antagonists for chronic cadmium intoxication.xe2x80x9d Toxicology 62(1): 1-25; Jones, S. G., M. A. Basinger, et al. (1982), xe2x80x9cA comparison of diethyldithiocarbamate and EDTA as antidotes for acute cadmium intoxication.xe2x80x9d Res Commun Chem Pathol Pharmacol 38(2): 271-8; Pages, A., J. S. Casas, et al. (1985), xe2x80x9cDithiocarbamates in heavy metal poisoning: complexes of N,N-di(1-hydroxyethyl)dithiocarbamate with Zn(II), Cd(II), Hg(II), CH3Hg(II), and C6H5Hg(II).: J. Inorg Biochem 25(1): 35-42; Tandon, S. K., N. S. Hashmi, et al. (1990), xe2x80x9cThe lead-chelating effects of substituted dithiocarbamates.xe2x80x9d Biomed Environ Sci 3(3): 299-305.
Researchers in oncology have evaluated the use of a number of dithiocarbamates in various cancer-treatment applications. For example, PCT WO 99/01118 of Chinery et al. discloses the use of antioxidants to enhance the treatment of hyperproliferative disorders such as cancer. The publication states that antioxidants can be combined with antineoplastic agents such as 5-fluorouracil (5-FU) to potentiate the activity of the antineoplastic agent to more effectively treat breast cancer, colon cancer, and other cancers. The publication indicates that dithiocarbamates which act as antioxidants are required, and specifically exemplifies dithiocarbamates of the formula, R2NC(S)SR, in which the nitrogen of the dithiocarbamate functionality is a tertiary amine. The nitrogen forms part of a heterocycle, or it is disubstituted by two alkyl groups or variants thereof.
Dithiocarbamates have also been used adjunctively in cis-platinum chemotherapy to prevent renal toxicity. For example, M. Hacker et al. in Cancer Res 42(11): 4490-4 (1982), reported on the effect of disulfiram (tetraethylthiuram disulfide) and diethyldithiocarbamate on the bladder toxicity and antitumor activity of cyclophosphamide in mice. See also Borch et al., U.S. Pat. No. 4,594,238 (disclosing the use of dialkyl-dithiocarbamates to reduce the toxicity of antineoplastic platinum compounds); U.S. Pat. No. 5,002,755 to Mitchell et al. (disclosing the use of dethyldithiocarbamate, di(hydroxyethyl)dithiocarbamate, and N-methyl, N-dithiocarboxy-D-glucamine to reduce nephrotoxicity of platinum compounds).
U.S. Pat. No. 5,187,193 to Borch et al. discloses the use of dithiocarbamate salts and acids to treat damaged bone marrow and to stimulate the production of bone marrow cell growth factors. U.S. Pat. No. 5,294,430 to Borch et al. discloses that dithiocarbamates can reverse the damage to the blood-forming function of the bone marrow (myelosuppression) caused by treatment with non-platinum antineoplastic agents. The general disclosure of both patents indicates that the nitrogen function of the dithiocarbamate can be part of a heterocyclic ring, or it can be substituted by two alkyl moieties or by one alkyl moiety and one hydrogen. Exemplary dithiocarbamates include diethyldithiocarbamate, N-methyl-glucamine dithiocarbamate and pentamethylene dithiocarbamate.
The CAS abstract for Japanese Kokai 55-015457 (CAS Abstract No. 1981:139788) discloses compounds having the formula RR1(CH2)mNHC(S)SCH2CHR2COR3, wherein: R and R1 can be methyl, ethyl, or together can form a phenyl ring; R2 is H or methyl; and R3is a saturated heterocyclic ring bound to the compound through nitrogen. The abstract indicates that these compounds have anti-inflammatory, anti-rheumatic, hypotensive, immunosuppressant, and anticancer activities.
The CAS abstract for Japanese Kokai 51-105016 (CAS Abstract No. 1977:30075) discloses compounds of the general formula (aralkyl)-NHC(S)SCH2CH(NH2)CO2R, wherein R is H, alkyl, alkenyl, alkynyl, cycloalkyl, or lower haloalkyl. The abstract indicates that these compounds display antibacterial, anticarcinogenic, and herbicidal activity.
The CAS abstract for Japanese Kokai 49-135942 (CAS Abstract No. 1975:156722) discloses symmetric compounds of the general formula ROOCCH(NH2)CH2SC(S)NHCH2-phenyl-CH2NHC(S)SCH2CH(NH2)COOR, and indicates that these compounds can be used as antimicrobial drugs and anticancer drugs.
The CAS abstract for French patent publication 2596987 (CAS Abstract No. 1988:548872) indicates that compounds of the formula NH2NHCSNHNH2 proved active against leukemia in a murine model, and also displayed antibacterial effects against Escherichia coli, Staphylococcus aureus, and tuberculosis in vitro.
Research into inflammation and cardiovascular disease has also focused on dithiocarbamates. For example, U.S. Pat. Nos. 5,380,747; 5,792,787; 5,783,596; 5,750,351; 5,821,260; 5,807,884; 5,811,449; 5,846,959; 5,877,203; and 5,773,209 to Medford, et al., teach the use of dithiocarbamate salts and acids for the treatment of cardiovascular and other inflammatory diseases. Examples include sodium pyrrolidine-N-carbodithioate, trisodium N,N-di(carboxymethyl)-N-carbodithioate, and sodium N,N-diethyl-N-carbodithioate. The dithiocarbamates disclosed in these patents all are disubstituted at the nitrogen of the dithiocarbamate function by alkyl or variant thereof, or the nitrogen is part of a heterocyclic ring. As mentioned above, the CAS abstracts for Japanese Kokais 55-015457, 51-105016, and 49-135942, and the CAS abstract for French patent publication 2425431, disclose various compounds characterized by the intermediate dithiocarbamate moiety xe2x80x94NHC(S)Sxe2x80x94, and disclose various inflammatory indications for such compounds.
In addition, the CAS abstract for Japanese Kokai 54-141726 (CAS Abstract No. 1980:181659) discloses N-substituted dithiocarbamates of the general formula NR2-alkylene-NHC(S)S-alkylene-CH(NHR)COOR (wherein R2 is H, alkyl, or forms a heterocycle with N), and indicates that the compounds inhibit leukocytopenia and act as adjuvants in the treatment of arthritis.
The CAS abstract for Japanese Kokai 48-005771 (CAS Abstract No. 1976:446399) discloses an N-substituted dithiocarbamate ester of the formula (isopropyl)-NHC(S)S-CH2-(pyridine)-CH2O2NHR, and indicates that the compound was hypotensive in spontaneously hypertensive rats.
U.S. Pat. Nos. 4,173,644, 4,120,972, and 4,120,966 to Brown et al. disclose 2-(5-methyl-4-imidazolylmethylthio)ethyl N-methyldithiocarbamate, and indicate that the compound can act as a histamine H2-antagonist, and is thus useful as an anti-inflammatory agents and as an inhibitor on the effects of histamine on blood pressure.
PCT WO 00/00192 filed by Boyle at el. discloses cyclic dithiocarbamates, of the formula R1R2NC(S)SR, wherein R1 and R2 constitute a heterocycle that includes the nitrogen of the dithiocarbamate moiety. The reference indicates that the compounds are useful to ameliorate or prevent inflammation.
U.S. Pat. No. 4,166,866 to Wight et al. disclose the use of thioesters of dithiocarbanilic acid or corresponding aryl-substituted dithiocarbanilic acids as immunosuppressants.
U.S. Pat. No. 3,875,170 to Matsumoto et al. disclose the use of pyridine bis(dithiocarbamate) derivatives as anti-hypertensive and anti-inflammatory agents.
U.S. Pat. No. 4,202,832 discloses thiocarbamoylthio fatty acids of the formula aryl-alkylene-NHC(S)S-alkylene-X, wherein X is an acid, ester, amide, or cyano, and indicates that the compounds are useful lipid lowering agents.
U.S. Pat. No. 5,563,159 to Kusaba et al. discloses dithiocarbinimide derivatives of dithiocarbamate esters useful as agaricidal, fungicidal and insecticidal agents.
U.S. Pat. No. 5,344,842 to Missbach discloses thiosemicarbazone derivatives that are useful for treating rheumatoid-type diseases.
It is an object of this invention to provide new methods, compositions, and strategies for treating hyperproliferative disorders, including cancer.
Another object of the present invention is to provide methods of improving the efficacy, and/or reducing the toxicity, of antineoplastic agents administered in the treatment of hyperproliferative disorders.
It is another object to provide new methods and compositions to treat VCAM-1 mediated diseases such as cardiovascular disease and inflammatory disorders.
It is another object to provide new methods of using N-substituted dithiocarbamate esters in the treatment of biological disorders.
It is still another object to provide new classes of N-substituted dithiocarbamate esters, and pharmaceutical formulations from such classes.
Certain N-substituted dithiocarbamate esters have been identified that have activity against hyperproliferative conditions. These compounds can be used to treat hyperproliferative conditions alone, or can be used in combination with one or more other antineoplastic agents. When used in combination with another antineoplastic agent, the combination can inhibit cellular proliferation to a greater extent than either compound administered individually.
Moreover, the combined dosage of antineoplastic agents with these N-substituted dithiocarbamate esters exhibits a desired degree of selectivity with respect to transformed (for example cancerous) versus non-transformed cell types, indicating that the compounds are more toxic to transformed cells than normal cells. In other words, the non-transformed cell types are less susceptible to the growth-inhibitory effects of a combined treatment than transformed cell types. These discoveries provide a therapeutic basis for the use of these N-substituted dithiocarbamate esters in the treatment of cancer and other diseases characterized by hyperproliferative cell growth.
The N-substituted dithiocarbamate esters of the present invention contain the dithiocarbamate functionality (xe2x80x94NR2C(S)Sxe2x80x94), in which one of the R groups is hydrogen. The xe2x80x9cN-substituted dithiocarbamate esters,xe2x80x9d as defined in more detail herein, thus all have a carbamate nitrogen with one hydrogen substituent. It has surprisingly been found that these N-substituted dithiocarbamate esters have independent chemotherapeutic activity even though many of these compounds are not antioxidants. The compounds may also potentiate the activity of antineoplactic agents.
A preferred class of N-substituted dithiocarbamate esters is defined by the following general formula (I): 
a) wherein:
b) X is selected from alkyl, alkenyl, alkynyl, heterocyclic, heteroaryl, aryl, aralkyl, heterocyclicalkyl, heteroarylalkyl, alkaryl, alkylheterocyclic, or alkylheteroaryl which can be optionally substituted;
c) Y is selected independently from H, CN, OR, OC(O)R, C(O)NR1R2, C(O)R, NR1R2, C(O)(OR), amino acid, alkyl, alkenyl, alkynyl, heterocyclic, heteroaryl, aryl, aralkyl, heterocyclicalkyl, heteroarylalkyl, alkaryl, alkylheterocyclic, or alkylheteroaryl which can be optionally substituted; and wherein R, R1 and R2 are independently H, alkyl, alkenyl, alkynyl, heterocyclic, heteroaryl, aryl, aralkyl, heterocyclicalkyl, heteroarylalkyl, alkaryl, alkylheterocyclic, or alkylheteroaryl which can be optionally substituted; and
d) linker1 and linker2 are independently alkyl, alkenyl, alkynyl, heterocyclic, heteroaryl, aryl, aralkyl, heterocyclicalkyl, heteroarylalkyl, alkaryl, alkylheterocyclic, or alkylheteroaryl, which can be optionally substituted and wherein linker1 can be a direct bond.
In another embodiment, Y is selected independently from CN, OR, OC(O)R, C(O)NR1R2, C(O)R, NR1R2, and C(O)(OR).
Another example of compounds is defined by the following structure (II): 
wherein:
X is a heterocycle or heteroaryl moiety; Y is CN, OR, OC(O)R, C(O)NR1R2, C(O)R, NR1R2, or C(O)(OR); n is 1, 2, 3, or 4 and m is 1, 2, 3, 4, 5, or 6.
The invention thus provides:
1. Defined N-substituted dithiocarbamate esters, and pharmaceutical formulations of such N-substituted dithiocarbamate esters;
2. The use of defined N-substituted dithiocarbamate esters in the treatment of cellular hyperproliferation;
3. The use of N-substituted dithiocarbamate esters in combination with antineoplastic agents in the treatment of cellular hyperproliferation; and
4. The use of N-substituted dithiocarbamate esters to potentiate the efficacy of antineoplastic agents.
It has also been discovered that the defined N-substituted dithiocarbamate esters inhibit the expression of VCAM-1, and thus can be used to treat disorders mediated by VCAM-1. Inflammatory disorders that are mediated by VCAM-1, and which can be treated using the N-substituted dithiocarbamate esters of the present invention, include rheumatoid arthritis, osteoarthritis, asthma, dermatitis, psoriasis, cystic fibrosis, and multiple sclerosis. Cardiovascular disorders that are mediated by VCAM-1, and which can thus be treated using the N-substituted dithiocarbamate esters of the present invention, include atherosclerosis, post-angioplasty restenosis, coronary artery diseases, angina, and small artery disease.
Thus, in still further embodiments the invention provides:
1. Pharmaceutical compositions that comprise a VCAM-1 inhibiting amount of an N-substituted dithiocarbamate ester of the present invention, or its pharmaceutically acceptable salt;
2. Methods for treating diseases or disorders mediated by VCAM-1 by administering an effective amount of a N-substituted dithiocarbamate ester of the present invention.
3. Methods for treating cardiovascular and inflammatory disorders by administering an effective amount of a N-substituted dithiocarbamate ester of the present invention.
In yet another embodiment, certain of these N-substituted dithiocarbamate esters act as inducers of a phase II enzyme, for example, including glutathione S-transferase, UDP-glucuronosyltransferase, and/or quinone oxidoreductase I (NQ01). This can be confirmed using the method described in De Long et al., Proc. Natl Acad Sci USA 83(3):787-791 (1986) and Talalay, Adv. Enzyme Regul. 28:237-250 (1989); Prochaska et al., Cancer Res. 48(17):4776-4782 (1988).